<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子阴影</title>

    <style>
        div {
            width: 200px;
            height: 200px;
            border-radius: 50%;
            box-shadow: inset 20px 20px 20px 20px gray;
        }
    </style>
</head>

<body>
    <div>

    </div>
</body>

</html>